Celiac sprue is an immune disease of the small intestine that is triggered by dietary gluten. A fundamental molecular understanding of celiac sprue pathogenesis is essential for the development of improved diagnosis and disease management strategies. Over the past few years, we have contributed to this endeavor in the following ways: (i) We established an intimate link between the immunotoxicity of gluten and its proteolytic resistance in the GI tract;(ii) We translated this insight into the design and development of promising oral enzyme therapies ("glutenases");(iii) We developed chemical reagents, X-ray crystallographic insights and biochemical assay systems to probe transglutaminase 2 (TG2), whose relevance to celiac pathogenesis is generally acknowledged but inadequately understood;(iv) We harnessed these molecular tools to show that TG2 is ordinarily inactive in the small intestine, but is transiently activated by innate inflammatory signals;(v) We solved the X-ray crystal structure of DQ2, and investigated the kinetics and thermodynamics of gluten peptide interaction with this disease associated HLA;and (vi) We exploited these structural and biochemical insights to identify gluten peptide analogues that block DQ2- mediated gluten antigen presentation to patient-derived inflammatory T cells. Our Specific Aims during the next proposal period are to: (i) Develop biomarkers to monitor in vivo glutenase efficacy in pilot proof-of-concept human clinical trials;(ii) Understand the mechanism and consequences of transient TG2 activation in the celiac small intestine;and (iii) Develop improved blockers of DQ2 mediated antigen presentation, and improved assays to quantify the efficacy of these blockers. Together, these studies will enhance our knowledge of gluten-induced pathogenesis in celiac sprue, and could also lead to new opportunities for celiac diagnosis and/or therapy. PUBLIC HEALTH RELEVANCE: Celiac sprue is a gluten-induced autoimmune disease for which no therapies are currently available other than an expensive and highly restrictive diet. During the past funding period, we have investigated selected aspects of the molecular pathogenesis of this disease, and have started to translate these insights into practical tools for disease management. During the next proposal period we propose to continue such studies.